ES2436637T3 - Procedure to dry a compressed gas and compressor group equipped with a dryer - Google Patents

Abstract

Procedure for drying a compressed gas from an outlet of a compressor, where a dryer equipped with a housing (2) with a drying zone (3) and a regeneration zone (5), and a drum ( 9) rotating inside the housing (2), which contains a regenerable drying agent (8), wherein the drying agent (8) is successively transferred through the drying zone (3) and through the regeneration zone ( 5), and where the compressed gas to be dried is conducted through the drying zone (3) while a regeneration gas is conducted through the regeneration zone (5), characterized in that said regeneration zone is divided into a first subzone through which the first regeneration gas flow is directed, in the form of a hot compressed gas coming from the compressor outlet, and a second subzone through which a second regeneration gas flow is directed; and that the second regeneration gas flow has a relative humidity less than the first regeneration gas flow; and because the second regeneration gas flow is composed of a fraction of the compressed gas leaving an outlet in the drying zone (3).

Description

Procedure to dry a compressed gas and compressor group equipped with a dryer

[0001] The present invention relates to a process for drying a compressed gas and a compressor group equipped with a dryer.

[0002] Specifically, the invention relates to a dryer equipped with a rotating drum containing a regenerable drying agent, said drying agent, as a consequence of the rotation of the drum, alternatively is carried by two zones of the dryer, where in one area, specifically, a drying zone, said drying agent is used to dry a compressed gas and in the other zone, more specifically, a regeneration zone, said drying agent is regenerated by putting this drying agent in contact with a hot gas.

[0003] As a result of the rotation of the drum, the regenerated drying agent will end up in the drying zone. In order to improve the performance of the dryer, it is practical and usual to provide the drum with a third zone, indicated as a cooling zone, said cooling zone allows the drying agent to cool so that said drying agent can adsorb much more moisture.

[0004] By using such a dryer to dry a compressed gas from a compressor, a portion of said compressed gas is cooled to subsequently be guided through the drying zone of the dryer, where the drying agent in this drying zone extracts the humidity of said gas, which consequently results in a dry gas with a low pressure dew point.

[0005] The remaining fraction of the compressed gas coming from the compressor and which is still hot due to compression, is conducted through the regeneration zone of the dryer, where said hot gas desorbs the moisture present in the drying agent, where the agent The drying agent is regenerated to allow later, in a new cycle, that it can be reused in the drying zone to dry the compressed gas.

[0006] A disadvantage is that the compressed gas used for regeneration has a relatively high humidity, as a result of which the drying efficiency is not optimal.

[0007] The foregoing has the unfavorable result that when the drying agent is subsequently taken to the drying zone, this drying agent can only absorb a limited amount of moisture from the gas being guided through the drying zone.

[0008] The heat of the compressed gas is used to regenerate the drying agent in the regeneration zone, so it should be noted that as the temperature of the compressed gas increases, the drying process improves and the efficiency of the installation increases accordingly.

[0009] The temperature of the compressed gas used for regeneration can be increased by the installation of a heating element or the like, before the gas is conducted through the regeneration zone.

[0010] A disadvantage of this is that heating the flow of gas used for regeneration is quite expensive in view of the continuous increase in the price of energy.

[0011] The invention aims to overcome one or more of these and / or other disadvantages.

[0012] For this purpose, the invention relates to a compressor group equipped with a compressor with an outlet, and a dryer equipped with a housing containing a drying zone and a regeneration zone, and a rotating drum in the housing with a regenerable drying agent therein and drive means for rotating the drum so that the drying agent is moved successively through the drying zone and through the regeneration zone, where the compressor outlet is connected through a pressure line at the entrance of the drying zone; wherein said regeneration zone comprises at least two subzones, namely a first subzone with a first input for the supply of a first flow of regeneration gas, and a second subzone with a second input for the supply of a second gas flow of regeneration; wherein to said pressure duct, between the compressor and the inlet of said drying zone, a branch is connected that connects to said first inlet of the first subzone; and where an outlet of said drying zone connects via a connection conduit to the second inlet of the second subzone, so that the relative humidity of said second regeneration gas flow is less than that of the first gas flow of regeneration. An advantage of a compressor group according to the invention is that the drying agent in the second subzone comes into contact with a gas flow whose moisture content is considerably lower compared to the gas flow flowing through the first subzone to regenerate the drying agent in the conventional manner.

[0013] Therefore, during the regeneration phase, even more moisture can be extracted from the drying agent than in the conventional manner, in other words, in this way additional drying takes place, at which

we can call deep drying, which causes the drying agent to absorb more moisture from the gas to be dried in a subsequent drying phase. A dryer according to the invention therefore has better performance.

[0014] According to a preferred embodiment of a compressor group according to the invention, a heat exchanger is provided in said connecting conduit.

[0015] An advantage of this is that the second regeneration gas flow, before being conducted through the second subzone, can be heated by said heat exchanger, as a result of which said gas flow can extract more moisture of the drying agent.

[0016] By increasing the temperature of the gas used for regeneration, the drying process will improve and consequently the efficiency of the dryer will increase.

[0017] Another advantage is that it is not necessary to heat the entire gas flow through the regeneration zone, but the second regeneration gas flow directed through the second subzone will suffice.

[0018] This entails a number of advantages since a relatively small heat exchanger can be used, which results in energy savings and a more compact installation.

[0019] The invention also relates to a process for drying a compressed gas from an outlet of a compressor, in said method a dryer equipped with a housing containing a drying zone and a regeneration zone, and a drum is used. rotating in the housing, with a drying agent inside, where the drying agent is moved successively through the drying zone and the regeneration zone, and in which the compressed gas to be dried is conducted through the zone drying while a regeneration gas is conducted through the regeneration zone, where said regeneration zone is divided into a first subzone through which a first regeneration gas flow is conducted, in the form of a compressed gas hot from the outlet of the compressor, and a second subzone through which a second flow of regeneration gas is conducted, and in which the second flow of regeneration gas has a humid ad relative less than that of the first regeneration gas flow, and in which the second regeneration gas flow is composed of a fraction of compressed gas leaving an outlet in the drying zone.

[0020] In order to better show the characteristics of the invention, by way of example without limitation, several preferred embodiments of a dryer and a compressor group according to the invention as well as a method of drying are described below. a compressed gas, with reference to the accompanying drawings, in which: Figure 1 schematically and in perspective view represents a part of a dryer with a compressor group; Figure 2 schematically represents a compressor group equipped with a dryer according to the invention; Figure 3 schematically represents the plane of a dryer of a compressor group according to the invention.

[0021] Figure 1 shows a part 1 of a dryer of a compressor group according to the invention, for compressed gas. The part 1 of the dryer is equipped with a housing 2 with a drying zone 3, a cooling zone 4 and a regeneration zone 5 inside, which according to the specific feature of the invention comprises two subzones, a first subzone 6 and a second subzone 7 respectively.

[0022] Preferably, said first subzone 6 connects to the end of the drying zone 3, while the second subzone 7 connects to the first subzone 6 followed by the cooling zone 4 which in turn connects to the beginning of the zone drying 3.

[0023] Therefore, the first subzone 6 is located at the beginning of the regeneration zone 5, or in other words, in the part of the drying zone 3 by means of which, during the operation of the dryer, the agent wet drying 8 enters the regeneration zone, while the second subzone 7 is located at the end of the regeneration zone 5, or, in other words, in the part of the regeneration zone through which the regenerated drying agent 8 leaves of the regeneration zone 5 and enters the cooling zone 4.

[0024] By "at the end of the drying zone 3" reference is made to the part of the drying zone 3 whereby the wet drying agent 8 leaves the drying zone 3 during the rotation of the drum 9, while by "the principle of the drying zone 3" refers to the part of the drying zone 3 through which the regenerated drying agent 8 enters.

[0025] In the housing 2 a rotating drum 9 is mounted which is equipped with a drying agent 8, also called desiccant.

[0026] The dryer 1 is also equipped with drive means, not shown in the figures, for example in the form of an engine, to make it possible to rotate the drum 9 so that the drying agent 8 is moved successively through the drying zone 3, the regeneration zone 5 and the cooling zone 4.

[0027] Figure 2 shows a compressor group according to the invention comprising, in addition to said part 1, a pressure line 10 for connecting the outlet of a compressor 11 and an inlet of the drying zone 3. The compressor 11 It is also part of the compressor group.

[0028] To said pressure line 10, between the outlet of the compressor 11 and the inlet of the drying zone 3, connects a branch 12 which is connected to a first inlet of said first subzone 6.

[0029] In addition, a return duct 13 is equipped for gas flows, used for regeneration and cooling, said return duct 13 connects the common outlet of the first and second sub-zones 6 and 7 of the regeneration zone 5 and of the cooling zone 4 to the pressure duct 10 and ends there near a venturi 14 equipped in the pressure duct 10. A cooler 15 is equipped in this return duct 13.

[0030] In the drying zone 3 there is, on the one hand, a discharge point 16 along which the dried gas can be discharged for later use and on the other hand, a connection duct 17 that conducts a fraction of the dried gas through the secondary side of a heat exchanger 18, and subsequently conducts this fraction through the second subzone 7 of the regeneration zone 5.

[0031] In the pressure line 10 between the compressor 11 and the venturi 14 an aftercooler 19 is provided.

[0032] The process according to the invention for drying a compressed gas is very simple and is as follows:

[0033] The flow directions are indicated in the figures. Arrow A shows the direction of the main flow through the drying zone 3 of the dryer. The direction of the remaining gas flow through the regeneration and cooling zone, in the example shown is in the opposite direction with respect to the flow direction A of the main flow, as illustrated by arrows B, D and E. The arrow C indicates the direction of rotation of the drum 9 in the dryer housing 2.

[0034] The gas to be dried, coming from the compressor 11 or at least a substantial portion thereof, flows, in the form of a main flow, after passing through the aftercooler 19, through the drying agent 8 in the drying zone 3 towards the exit of the drying zone 3, where, when making contact with the drying agent 8, said drying agent adsorbs moisture. The gas dried in this way is discharged by a discharge point 16 to a downstream network of consumers.

[0035] The drum 9 transfers the drying agent 8 loaded with moisture to the first subzone 6 of the regeneration zone 5, where the moisture of the drying agent 8 is desorbed by contact of this drying agent 8 with a first flow of regeneration gas in the form of a hot compressed gas which, by a branch 12, is supplied from the outlet of the compressor 11, to fulfill as such a first regeneration of the drying agent 8, making use of the compression heat present in said first regeneration flow.

[0036] According to a specific feature of the invention, at the end of the movement of the drying agent 8 through the regeneration zone, this drying agent is still dried in the second subzone 7 of the regeneration zone 5 more than it had been possible so far, by putting the drying agent 8 in contact with a second flow of regeneration gas whose relative humidity is less than that of the first flow of regeneration gas.

[0037] For this purpose, the second flow of regeneration gas in this case consists of a gas that is branched off the dried gas leaving the drying zone 3 and which, before being supplied to the regeneration zone 5 by means from the inlet of the second subzone 7, it is conducted through the secondary side of the heat exchanger 18, in which said gas flow is heated, to decrease the partial pressure of the water present in this gas.

[0038] It is clear that in this way the moisture content of the drying agent 8 during regeneration can be considerably reduced due to the fact that the drying agent 8 is subsequently dried in the second subzone 7 of the regeneration zone 5 making use of a hot dry gas with low relative humidity. This is the most important advantage of the dryer and the process according to the invention.

[0039] As the drum 9 continues to rotate, more moisture is extracted from the drying agent 8, until the drying agent 8 reaches the drying zone 3, after being cooled in the cooling zone, free of adsorbed moisture, so that the regenerating drying agent 8 as such can be used during a subsequent drying cycle in the drying zone 3.

[0040] As such, the drying agent 8 is alternately conducted through the drying zone 3 and subsequently through the regeneration zone 5, in a continuous or discontinuous revolution movement.

[0041] According to the invention, it is appropriate that a fraction of the flow of dried main gas be used to cool the regenerated hot drying agent 8 in the transition between the regeneration zone 5 and the drying zone 3 in the cooling zone 4, before said drying agent 8 comes into contact with the main flow in the drying zone 3.

[0042] The presence of such a cooling zone 4 is, after all, advantageous because the main flow does not come into contact with the hot drying agent 8 which is not capable of adsorbing liquid and which would cause the leakage of the wet gas through the dryer. 1. Consequently, drying is optimized in this way.

[0043] Thanks to the venturi 14, a local pressure drop is generated in a known manner, which results in that the outlet of the regeneration zone 5 remains under a lower pressure than the outlet of the drying zone 3 located

10 on the opposite side of the drum 9, as a result of which a fraction of the cold main gas flow from the outlet of the drying zone 3 flows to the outlet of the regeneration zone 5, through the cooling zone 4 located between the drying zone 3 and the regeneration zone 5.

[0044] By conducting this flow through the cooling zone 4, the regenerated hot drying agent 8 will be cooled with an advantageous effect, before said drying agent 8 is used to dry the main gas flow.

[0045] The lower pressure described above also causes the gas coming from the drying zone 3 to flow through the heat exchanger 18, into the second subzone 7. This particular flow is made possible by removing dry gas 20 in the correct position, namely in the position where the dynamic pressure is the lowest. Thus, no blowers are required for this system.

[0046] The gas used for regeneration and cooling of the drying agent 8, after flowing through the respective zones, is collected and cooled by a cooler 15, after which this gas is added to the main gas flow, which subsequently , is in turn driven through the drying zone 3.

[0047] Figure 3 shows an example of a schematic drawing of a part 1 of a dryer according to the invention, where the different sectors or zones have been made visible.

[0048] This figure shows in particular how the regeneration zone 5 is divided into two subzones 6 and 7, where in this case the regeneration zone 5 extends over a circumferential angle of almost 90 degrees.

[0049] In this case, the first subzone 6 extends over an angle of 75 degrees, while in this example the second subzone 7 extends over an angle between 5 degrees to 30 degrees, and in this case over an angle 35 of almost 15 degrees.

[0050] In this example, the drying zone 3 comprises a circular sector of 255 degrees, while the remaining part of 15 degrees, between the second subzone 7 and the drying zone 3, forms the cooling zone 4 in the housing. cylindrical 2 of the dryer.

[0051] The figure shows in what sense the different areas of the drum will preferably be traversed

9.

[0052] It is obvious that the second regeneration gas flow can also be heated by conducting said flow through a heating element or the like, not shown in the figures.

[0053] The gas that is conducted through the second subzone 7 does not necessarily have to come from the dryer itself, however, it can also originate from an external source of dried gas.

Claims (6)

1. Procedure for drying a compressed gas from an outlet of a compressor, where a dryer equipped with a housing (2) with a drying zone (3) and a regeneration zone (5) is used, and a 5 drum (9) rotating inside the housing (2), which contains a regenerable drying agent (8), wherein the drying agent (8) is successively transferred through the drying zone (3) and through the zone of regeneration (5), and where the compressed gas to be dried is conducted through the drying zone (3) while a regeneration gas is conducted through the regeneration zone (5), characterized in that said regeneration zone is divided into a first subzone through which the first regeneration gas flow is directed, in the form of 10 a hot compressed gas from the compressor outlet, and a second subzone through which a second flow of regeneration gas is directed; and that the second regeneration gas flow has a relative humidity less than the first regeneration gas flow; and because the second regeneration gas flow is composed of a fraction of the compressed gas leaving an outlet in the drying zone (3). Method according to claim 1, characterized in that the second regeneration gas flow is heated before being conducted through the second subzone (7). 3. Method according to claim 1 or 2, characterized in that the second regeneration gas flow is heated by conducting said flow through a heat exchanger (18) and / or an external heating element 20 or the like. Method according to any one of claims 1 to 3, characterized in that the first and the second regeneration gas flow are collected at the common outlet of the first subzone (6) and the second subzone (7) and are subsequently conducted, to through a return duct (13) to an inlet of the drying zone (3), by 25 medium of a cooler (15). 5. Compressor group equipped with a compressor (11) that has an outlet, and a dryer equipped with a housing (2) with a drying zone (3) and a regeneration zone (5) inside, and a drum (9), which can rotate inside the housing (2) with a regenerative drying agent (8) in its interior and drive means for rotating the drum (9), so that the drying agent (8) is successively moved through the drying zone (3) and through the regeneration zone (5), characterized in that the compressor outlet (11) connects through a pressure line (10) to an inlet of the drying zone; because said regeneration zone (5) comprises at least two subzones, namely a first subzone (6) with a first inlet for the supply of a first flow of regeneration gas, and a second subzone (7) with a second inlet for the supply of A second flow of regeneration gas; because a branch (12) connects to said pressure conduit (10), between the compressor (11) and the inlet of the drying zone (3), said branch (12) connects to said first inlet of the first subzone (6) ); and because an outlet of said drying zone (3) connects to the second inlet of the second subzone (7) by means of a connecting duct (17), so that the relative humidity is lower than that of the first gas flow Regeneration 6. Compressor group according to claim 5, characterized in that a heat exchanger (18) is provided in said connecting conduit (17). 7. Compressor group according to claim 5 or 6, characterized in that the first subzone (6) and the second subzone (7) have a common output.